1. Field of the Invention
The present disclosure relates generally to wireless electronic devices, and more particularly, to searching for a network by a device supporting a plurality of communication methods.
2. Description of the Related Art
As wireless electronic devices such as smart phones have proliferated, data service use has explosively risen. The rise in data demand strained the loads of 2G/3G mobile communication systems, leading to the launch of a Long Term Evolution (LTE) system which provides a high speed data service. The LTE system provides a high data transmission rate as compared to a 2G/3G mobile communication system, but is a data exclusive network formed with an all-IP network and cannot thereby support voice service using only LTE system equipment.
Therefore, until an all-IP network is formed, in order to simultaneously support voice and data services, Circuit Switch-FallBack (CSFB) and Simultaneous Voice and LTE (SVLTE)/Simultaneous GSM & LTE (SGLTE) methods have been introduced.
The CSFB method disconnects an LTE data communication connection when a voice call is received or when a voice call is initiated by a device, and switches to a 3G network connection (e.g. based on Wideband Code Division Multiple Access (WCDMA)). In the CSFB method, a 3G network simultaneously supporting a voice service and a data service such as a WCDMA network is stably operated, rendering the method desirable to service providers. The SVLTE/SGLTE method has been introduced and used by service providers using a 2G/3G network (e.g., CDMA2000 EV-DO) in which voice and data communication are not simultaneously supported. The SVLTE/SGLTE method requires an antenna and a Radio Frequency (RF) chip in the electronic device for each service in order to simultaneously support voice service and LTE service. Accordingly, in the SVLTE/SGLTE method, the number of components increases and power consumption, weight, heat, and electromagnetic waves generated by a terminal may increase considerably.
In a “no-service” state, an electronic device using the SVLTE/SGLTE method may use an algorithm that searches for signals over a full band of a network, which includes 2G roaming frequencies as well as 3G and 4G designated frequencies. Due to this extensive scanning, a problem arises in that a network search time is long and a recovery time becomes slow.